Numerous dental composites for universal use are known according to the prior art, i.e. dental composites that meet the requirements for restoration of the tooth structure of all cavity classes I, II, III, IV, and V according to G. V. BLACK. From the class of dental composite materials, basically only inorganic-organic hybrid materials with substantial amounts of inorganic fillers, such as dental glass or mineral nano-agglomerates, are suitable for this purpose. Introduced in the 1980s, the micro-filler composites with pre-polymer fillers are not suitable for use in lateral tooth regions (classes I and II) due to their limited resistance to wear (abrasion resistance) and fracture resistance (flexural strength). A high filler content is advantageous in order for the cured composite to attain good mechanical properties and to concurrently reduce the polymerisation shrinkage occurring in the course of the curing process. These properties are also crucial for the long-term success of any therapy involving dental composites.
However, not only the materials properties of a cured dental composite, but also the processing by the user prior to polymerisation is crucial for the long-term success of medical management. The application from the packaging, introduction into the cavity, adaptation to the tooth structure, and shaping of the composite layer are extremely dependent on the plasticity and tackiness of the non-polymerised material. Especially the desired high amounts of inorganic fillers introduce disadvantageous thixotropy into the system due to their surface interactions. Elicited by polar interactions between oxidic filler particles (e.g. silicates), these forces may be disturbed temporarily through shearing, and high shear thinning is characteristic of the composites. The same interactions lead to tackiness on the surface of the composite. Soft composites, in particular, tend to show disadvantageous tackiness since they have better flow properties.
The visco-elastic flow properties are usually determined with rheometers. According to the current prior art, the consistency of composites is corrected solely through slight adjustment of the filler fraction. This is associated with an uncontrolled change of the tackiness. It is still not customary to this day to even measure the tackiness of composites, let alone to adjust it in controlled manner. The product properties therefore vary greatly such that the variation in quality is apparent to the user.
Flowable dental composites are desired to possess certain usage and/or handling properties for dental management or dental lab work pieces involving them to be reliable and successful, i.e. the plasticity not being too firm (sufficient flow properties) and the tackiness (at the application instrument) being low.